The present invention relates generally to electrical heaters, and more particularly, to an electrical heater that can be used to heat the sump of air conditioning compressors.
Commercial air conditioning compressors commonly include a sump heater that is externally mounted in close relation to the compressor housing. The sump heater maintains the compressor at a temperature which prevents condensation of the refrigerating gas, namely freon, in the compressor. Otherwise, the condensing freon will migrate to the oil in the compressor and thereby expose the compressor parts to temperatures below that at which they can reliably operate, creating a potential for failure.
Since such compressors often have life-time warranties, it is important that the sump heater be adapted for long-term reliable operation. For example, since the sump heater is a relatively inexpensive component of an air conditioning compressor, costly service calls and repairs associated with a breakdown of the sump heater during operation in the field are particularly undesirable. Moreover, in view of the long-term reliability requirements for air conditioning compressors, they also commonly undergo extensive and rigorous reliability testing during manufacture. Again, failure of the compressor during such testing can impede the manufacturing processing line and is particularly inefficient and frustrating when the failure is caused by a relatively inexpensive component such as the sump heater.
Accordingly, in view of the foregoing, the present invention provides an electrical sump heater which is adapted for long-term reliable use.
Another object is to provide an electrical heater as characterized above which is adapted for consistent and repeatable manufacture within design standards.
These and other features and advantages of the invention will be more readily apparent upon reading the following description of a preferred exemplary embodiment of the invention and upon reference to the accompanying drawings wherein: